What a DXA Scan Can Reveal About Your Bone Health and Fracture Risk: This non-invasive screening test will show if you have the bone-thinning disease osteoporosis.
"More women suffer osteoporotic fractures each year in the United States than are diagnosed with breast cancer, experience a heart attack, or have a stroke combined," says Alana Serota, MD, an osteoporosis expert at the Weill Cornell-affiliated Hospital for Special Surgery. "Osteoporosis is a common and debilitating condition for which safe and effective treatments exist, but it is woefully under-recognized and undertreated."
Undergoing a dual-energy X-ray absorptiometry, or DXA, scan is the first step to identifying if you are at risk of fracture.
"A DXA scan provides the aerial bone density of specific areas that are the most common sites of fracture, such as the first four lumbar vertebrae, the femurs (bones that run from your knees to your hips), and the non-dominant forearm," says Dr. Serota. The DXA scanner measures the amount of X-rays that pass through the bone from a high-energy and a low-energy beam; the difference in the two measurements indicates your bone density.
She notes that "DXA" is the correct medical abbreviation for the test, but you also may see it referred to as a "DEXA" scan.
What the Results Mean
A DXA scan's result is given as a "T score."
"A T-score compares your bone density to a normative database of healthy adult females at peak or ideal bone mass, measured in units of standard deviations (SD) explains Dr. Serota.
A T-score of-1.0 or above is normal bone density. You have low bone density (formerly called osteopenia) if your T-score is between -1.0 and -2.5. Osteoporosis is defined as a T-score of -2.5 or lower.
"Severe or established osteoporosis is a T-score of-2.5 or lower accompanied by a history of a low-trauma fracture, which is defined as a fracture caused by a fall from standing height or less," explains Dr. Serota.
Who Needs a DXA Scan
A DXA scan is recommended for all women age 65 and older, but age is not the only factor to consider.
"The International Society for Clinical Densitometry (ISCD) also advises DXAs for post-menopausal women younger than age 65 who have risk factors for low bone mass, such as low body weight, prior fracture, high-risk medication use, or a disease or condition associated with bone loss," says " Dr. Serota.
If you think a DXA scan is less important than a mammogram or a colonoscopy, consider this advice from Dr. Serota: "Osteoporosis is a silent thief; it does not cause symptoms or pain until you break a bone. Our skeletal 'bank account' is nearly full by age 20, with some consolidation into the early to mid-30s. Everything in life--menopause, illness, lifestyle choices, a nutrient-poor diet--withdraws from this 'fund.' The objective is to prevent the first fracture, and a DXA scan helps by showing us how much is in your 'bank account. "
Several medications are associated with bone loss and/or increased fracture risk. Some of these medications include:
* Glucocorticoids (both oral and inhaled steroids such as prednisone, cortisone, prednisolone, hydrocortisone, and methylprednisolone)
* Excess thyroid supplementation (dosing that is suppressive, not physiologic)
* Proton pump inhibitors used to treat gastroesophageal reflux disease and/or frequent heartburn, such as Prilosec, Prevacid, and Nexium
* Aromatase inhibitors used to treat breast cancer, including Arimidex, Aromasin, and Femara
* GnRH agonists used to treat endometriosis and uterine fibroids such as Lupron
* Opiate pain medications, such as hydrocodone and oxycodone
* Methotrexate (used to treat some cancers and rheumatoid arthritis)
* Cyclosporine (used to treat psoriasis)
* Loop diuretics (used to treat high blood pressure), such as Lasix
* Anticonvulsants such as Tegretol, Dilantin, and Depakote
* Anticoagulants such as heparin.
Several underlying medical conditions are also associated with low bone density and/or increased fracture risk. Those commonly seen include celiac disease, inflammatory bowel disease, rheumatoid arthritis, anorexia, and hyperparathyroidism, among others.
Lifestyle-related risk factors include smoking and alcohol intake above recommended guidelines. Dr. Serota notes that drinking cola and caffeinated beverages to excess also may be problematic, as is a diet deficient in protein. Exercise is important, but Dr. Serota cautions that excessive exercise in the absence of appropriate calories can be harmful to bones.
Improve Your Bone Health
There are simple steps to optimize bone health and cut the risk of fractures.
"Adequate dietary calcium is important. Those who cannot get enough calcium from diet will need to supplement. Nearly everyone living in the Northeast needs to supplement vitamin D to some degree, especially during winter months when the sun's ultraviolet rays are unable to activate vitamin D production in your skin. Sunscreen and aging also impair vitamin D production," says Dr. Serota. She also cautions that, though many other supplements for bone health are widely touted, there is little evidence for their usefulness and some evidence, such as in the case of strontium, for potential harms.
"Finally, if medical intervention is needed, we have a number of safe medications that are very effective at maintaining or even increasing bone density and decreasing fracture risk," concludes Dr. Serota.
WHAT YOU SHOULD KNOW
How often should you have a DXA scan? Here are recommendations and guidance on frequency of DXA scans provided by osteoporosis expert Alana Serota, MD.
* If we are expecting a rapid rate of change in bone density, such as in the early postmenopause or in the first few years after starting treatment for osteoporosis, we check bone density every year. Patients on medications that raise the risk of bone density loss, such as glucocorticoids, can be rechecked at even shorter intervals.
* In patients who are stable on therapy, every two years is reasonable. For patients with normal bone density or mildly low bone density after age 65, longer intervals have been recommended.
* Any change in health status, including weight loss of more than 10 pounds, new medical conditions, new medications, and, of course, falls and fractures, may prompt testing at shorter intervals.
Caption: A DXA scan analyzes the bone density at several fracture-prone areas, including the hip and the lumbar vertebrae.
Caption: Exercise helps slow the rate of bone loss and decreases the risk of falls and fractures, but exercise alone is not a treatment for osteoporosis. Dr. Serota advises that an appropriate exercise regimen includes aerobics, strength and resistance training, and daily balance work.
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|Publication:||Women's Health Advisor|
|Date:||Mar 30, 2019|
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